This Center assists investigators in the U.S.A. and abroad in the identification of arboviruses. The Center maintains a complete collection of virus seeds, antigens, and immune fluids which it uses for its own work as well as distributing them on request to specialized laboratories. During 1975, the Center received virus and/or antiserum to 84 strains from 18 countries. Viruses were identified from Venezuela, U.S.S.R., Senegal, Scotland, Norway, Malaysia, Indonesia, Ecuador, Brazil, Australia, Ethiopia, Thailand, Portugal, Kenya, and several areas of the U.S.A. At least 20 of these are either new viruses or new to the geographic region or host in which they were found. Serologic surveys of Turkey, Liberia, and Ghana were done. Serological tests to determine the etiology of Korean hemorrhagic fever, juvenile arthritis in Connecticut, and chromosome breakage in the Yanomama Indians were undertaken. New techniques for study of arboviruses were developed including type-specific identification of California group viruses by CF with one injection hamster sera, and trypsinized human O cells for the HI test. The goal for next year is the identification of 80 viruses from the Americas and other parts of the world. New techniques for study of the antigenic, biologic, and physico chemical properties of viruses of major human disease potential such as Crimean hemorrhagic fever-Congo, yellow fever, dengue, and Venezuelan encephalitis are being developed and will be stressed. BIBLIOGRAPHIC REFERENCES: Bowen, G.S., Tomori, O., Wulff, H., Casals, J., Noonan, A., and Downs, W.G. Lassa fever in Onitsha, East Central State, Nigeria, 1974. In press, Bull. Wld. Hlth. Org., 1976. Casals, J. Arenaviruses, Yale J. Biol. & Med. 48: 115-140, 1975.